Spring(ish) Bird Walk at Sandbar SP and South Hero Marsh

March 25 2016
1-4:30 PM
50 degrees F
West wind 10 mph
cloudy, damp. Following 12 hours of rain.

Twelve people joined us on this Friday Field Walk, a weekly series of trips led by UVM's Field Naturalist and Ecological Planning Programs. The cohort represented Ornithology students, FN/EP students, community members, and Green Mountain Audubon Society members. We spent about an hour at Sandbar State Park. The north edge of the causeway and beach holds the last ice on Lake Champlain, and has concentrated thousands of gulls and waterfowl. An apparent fish kill, perhaps alewife, was drifting under the ice, and gulls were patrolling ice edges to access these fish. Bald eagles are becoming more territorial as juvenile birds get harassed by adults on the sheer thermals in the milton foothills generated by a steady west wind.
A careful drive along the shoulder of the causeway allowed us to use the vehicle as a blind, minimizing the concern of dozens of notoriously skiddish wood ducks. Pintails, wigeons, mallards, and black ducks also filled the open pockets in the marsh and floodplain forest. Many of the species that have been sitting on the open lake all winter are finally accessing freshly-thawed ponds and flooded fields. Once the ice along these north-facing edges melts, I bet the waterfowl density inland will really pick up. The same pattern would probably be true down at Crown Point right about now.
There was a recent incidental observation by a third party of a small white-winged gull on the south side of the causeway. Perhaps a Boneaparte's Gull still in winter plumage, or perhaps a Thayer's or Little Gull? A mystery.

We moved to the South Hero Marsh, accessed by a rail trail off Tracy Road. Among other things, we had First of the Year Osprey, tree swallows, and northern flicker. We expected to find rusty blackbirds at this site, and despite the unseasonably warm winter and today's warm weather coming in from the south, the numbers of migrant icterids were surprisingly small. The water here has thawed since being 90% frozen on Tuesday.

Birders are reporting lots of activity in flooded fields lately, especially after all the rain. The forage available in these ephemeral fields is likely more plentiful than the thawed permanent wetlands. Waste grains and invertebrates in flooded corn fields, for instance, are plentiful, but can only be accessed during a short annual window in these sorts of conditions, whereas perennial ponds and marshes receive foraging pressure throughout the warmer months.

Posted on March 26, 2016 11:53 AM by sebeckett